On this issue there have been conflicting reports on just about everything. You have to be very selective with what you choose to believe to blame one side or the other. As I said, even if chemical weapons were used, it's not at all clear by who. It wasn't too long ago Carla Del Ponte from the UN's inquiry on this issue was stating publicly that eye-witness accounts paint the rebels as the ones who used the weapons, not Assad's forces. Kerry likes to think that only Assad has access to chemical weapons but the US's record on WMD intelligence is, i'm sorry to say, lacking to say the least. It wouldn't be the first time chemical weapons were used by non-governmental forces. Aum Shinrikyo used sarin in Tokyo. Rajneeshee carried out a bioterror attack in Dallas in '84. If these things can happen under our noses in the west, you really think rebels with funding and support from nation states can't get their hands on any, or manufacture some?